When people attend a large event, such as a football game, they are generally relegated to passively watching the show, without participating. An exception to this is when the crowd does “the wave”—people stand and then sit back down, following the people next to them. As the wave propagates through the stands, the motion is clearly visible at a great distance, creating an entertaining spectacle. Performing the wave gives people a way of feeling like they are contributing to the show.
This sort of audience participation can also be purposely designed and encouraged. For example, audience members might be handed different color cards based on their seat positions, and told to lift them above their heads at the proper moment. Similarly, large groups of performers can be trained to take coordinated actions in the stands to create different visual effects.